code: def test_audio_only(self, input_keys):
      input_keys += ["f0_hz"]
      inputs = {
          k: v for k, v in self.input_dict.items() if k in input_keys
      }
      outputs = self.preprocessor(inputs)
      self.assertAllClose(
          self.input_dict["power_db"],
          outputs["pw_db"],
          rtol=0.5,
          atol=30,
      )
  
file_path: ddsp/ddsp/training/preprocessing_test.py
imports: from absl.testing import parameterized
  from ddsp.core import resample
  from ddsp.spectral_ops import compute_power
  from ddsp.training import preprocessing
  import tensorflow
label_desc: Use image node_id 2 for calling the F0PowerPreprocessorTest obj's underlying member method code with example usage: obj.test_audio_only(input_keys) without return types